Hardware datasheet for the u-blox NEO-6 series GPS modules, document reference GPS.G6-HW-09005 per the file name. It covers module variants, pin assignment, supply and backup voltage requirements, antenna interface, UART, USB and I2C connections and mechanical dimensions. Technicians and makers use it to check power and backup supply on a GPS board, confirm serial data output, and diagnose antenna or timepulse problems, since NEO-6 modules are common in drone flight controllers and hobby receivers.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @datasheet. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.